The aforementioned related U.S. patent application teaches a method of treating pyrophoric elemental phosphorus-containing material to render it less pyrophoric. The treatment comprises treating such pyrophoric material while it is under a liquid blanketing layer with an oxygen-containing gas. A preferred blanketing liquid is water and either air, an oxygen-enriched gas stream, pure oxygen, and the like can be used as the oxygen-containing gas. Further details regarding the procedure whereby such elemental P.sub.4 -containing material can be converted to a less pyrophoric form can be found in the copending prior application, which is incorporated herein by reference.